The show is about Britain's Henry VIII and his six wives. The monarch is played by Irish actor Jonathan Rhys Meyers.
Season 3, which is to air next year, will follow the character as he marries Jane Seymour and Anne of Cleves, Showtime said.
Production is slated to begin June 16 in Dublin, Ireland, with Meyers set to return to the royal role.
"'The Tudors' is now a fixture for us at Showtime and we're on our way to completing the entire saga of all six wives of Henry VIII," Showtime President of Entertainment Robert Greenblatt said in a statement. "We are enormously proud of this show, the extraordinary cast, and the production team that recreates the grandeur of the Renaissance year in and year out. There is nothing like this anywhere on American television."